Various filter systems have been developed to filter water and wastewater. Typical filter systems include but are not limited to upflow filters/clarifiers, downflow filter/clarifiers and bi-flow filters as well as various combinations of the aforementioned filter systems. The terms filter and clarifier are used interchangeably herein and refer to a structure in which influent is directed through to remove at least some impurities. An upflow filter/clarifier is a structure in which influent is directed in an upward path to remove impurities. Conversely, the term downflow filter/clarifier refers to a structure in which the influent is directed in a downward path to remove impurities. A bi-flow filter/clarifier refers to a structure in which the influent is directed in both a downward path and an upward path to remove impurities. The upflow filters/clarifiers, downflow filters/clarifiers and bi-flow filters include one or more filter components.
A sludge blanket may be used as the filtering component in filter systems including but not limited to upflow filters/clarifiers. A sludge blanket is typically formed at a point of equilibrium between the lifting force of the influent traveling upwardly through a filter/clarifier and the counteracting gravitational force on the precipitates and/or flocculated particles in the influent. Specifically, at the point of equilibrium, the precipitates and/or flocculated particles gather and form a sludge blanket of a desired thickness and density. As influent travels through the sludge blanket, impurities in the influent are trapped in the sludge blanket.
Previously known sludge blanket filters/clarifiers suffer from a number of disadvantages. For example, prior known sludge blanket clarifiers do not have suitable means for effectively and efficiently evacuating sludge in the event that the sludge blanket should fall to the bottom of the filter or clarifier or an undesirable amount of sludge collects in the filter/clarifier. In existing systems, if the sludge blanket falls or an undesirable amount of sludge collects in prior known filters/clarifiers, the sludge is typically removed manually. This is a significant disadvantage as it undoubtedly leads to prolonged periods in which the filter/clarifier is rendered inoperable. Another disadvantage of prior known sludge blanket filters is the inability to uniformly distribute influent across the sludge blanket without the need for complex systems including vacuum systems. This again is a significant disadvantage. Specifically, if influent is not uniformly distributed across the entire area of the sludge blanket, the sludge blanket cannot filter to its maximum capacity. Moreover, if influent is concentrated in one or more small areas of the sludge blanket, holes can form in these areas of the sludge blanket. Obviously, influent passing through these holes in the sludge blanket will not be properly filtered.
Prior known devices employing a sludge blanket as a filtering component are also incapable of being readily retrofitted into existing filters. For example, if it was desired to convert an existing upflow filter using a bed of filter media as the filtering component to a filter that uses a sludge blanket as the filtering component, such conversion was not commercially practical with prior known devices. This is a significant disadvantage as an existing filter could not be used leading to the expenditure of considerable fluids for a new filter system.
Prior known sludge blanket clarifiers that employ a filter having a conical configuration require larger structures that undesirably increase the cost of the filter system. Prior known filter systems also cannot efficiently and cost effectively achieve a desired level of flocculation in the sludge blanket clarifier. Flocculation is the process in which impurities in the influent agglomerate making the impurities easier to filter. Previously known systems require excessive amounts of costly chemicals or other means to achieve a suitable level of flocculation.